The present invention relates to a method for determining the progression of the load torque in an internal-combustion engine.
Methods are known for determining the progression of the load torque applied to an internal-combustion engine during a combustion cycle of the engine, whereby the progression of the load torque is obtained both as a function of the progression of the angular velocity of the engine during the combustion cycle itself and as a function of the progression of the pressure inside at least one cylinder.
In particular, these methods envisage the use of at least one sensor outside the engine block so as to be able to reconstruct the progression of the pressure inside the cylinder. In fact, in some cases, a pressure sensor is mounted directly inside the combustion chamber of the cylinder so as to output a signal indicating the internal pressure. In other cases, the pressure inside the cylinder is obtained by means of a piezoelectric accelerometer mounted on the engine block, opposite the cylinder, so as to output an electric signal representing the vibrations of the engine block, which, as is known, are directly correlated to the progression of the internal pressure.
Therefore, the said methods for determining the load torque require a sensor outside the engine block, which generally involves not insignificant costs due to the sensor as such, the installation operations and any modifications which must be performed to the engine block in order to provide the seats suitable for receiving said sensor. Moreover, both the pressure sensor and the accelerometer, in view of the hostile conditions of the environment in which they operate, are subject to continuous mechanical and/or thermal stresses which could adversely affect the correct functioning thereof as well as reduce their average working life.
The object of the present invention is that of providing a method for determining the progression of the load torque in an internal-combustion engine, which does not have the drawback described above and by means of which it is possible to determine the load torque without modifying the engine block and without the aid of sensors outside the engine block itself.
According to the present invention, a method for determining the load torque in an internal-combustion engine is provided, characterized in that it comprises the steps of detecting the progression of a physical parameter indicating the instantaneous angular velocity of the said engine; determining the progression of the pressure inside at least one cylinder of the said engine as a function of the progression of the said physical parameter; and determining the progression of the said load torque as a function of the progression of the said physical parameter and the progression of the said internal pressure.